Lagged Associations of Metropolitan Statistical Area- and State-Level Income Inequality with Cognitive Function: The Health and Retirement Study

Neighborhood racial income inequality and cognitive health

INTRODUCTION

Neighborhood socioeconomic status (SES) has been linked to dementia, but the distribution of SES within a neighborhood may also matter.

METHODS

Data from 460 (47% Black, 46% White) older adults from the Michigan Cognitive Aging Project were linked to census tract-level data from the National Neighborhood Data Archive (NaNDA). Neighborhood SES included two composites reflecting disadvantage and affluence. Neighborhood racial income inequality was the ratio of median incomes for White versus Black residents. Generalized estimating equations examined associations between neighborhood factors and cognitive domains.

RESULTS

Neighborhood racial income inequality was uniquely associated with worse cognitive health, and these associations did not differ by participant race. Neighborhood disadvantage was only associated with worse cognitive health among Black participants.

DISCUSSION

Both the level and racial distribution of SES within a neighborhood may be relevant for dementia risk. Racial differences in the level and impact of neighborhood SES contribute to dementia inequalities.

HIGHLIGHTS

Black participants lived in neighborhoods with lower socioeconomic status (SES) than White participants, on average. Neighborhood SES and racial income inequality were associated with worse cognition. Effects of neighborhood racial income inequality did not differ across racial groups. Effects of neighborhood SES were only evident among Black participants.

The plasma derived exosomal miRNA-483-5p/502-5p serve as potential MCI biomarkers in aging

Alzheimer's disease (AD) is the leading cause of dementia and is rapidly becoming one of the most costly, fatal diseases, which is typically discovered in the late stage of molecular pathology, at which point medication intervention is irreversible. As a result, there is an urgent need for a low-cost, least-invasive way of screening cognitive impairment, with the goal of identifying persons at risk of AD. Mild cognitive impairment (MCI) has been described as a transitional state between normal cognitive aging and AD. Early detection and timely tracking of MCI can to some extent prevent the progression towards AD. We found a population in Northwestern China has a comparatively high prevalence of MCI. Continued education, consistent exercise, and a secure financial situation can all help older people maintain cognitive function. Due to the critical role of circulating microRNAs in intercellular signaling and the perturbations thereof, their investigation has assumed paramount significance in elucidating various pathological conditions. Numerous investigations have substantiated the significance of circulating miRNAs specifically in MCI. Here, we evaluated miR-483-5p (Area Under the Curve (AUC) is 0.901, sensitivity 79.2 % and specificity 100 %) and miR-502-5p (AUC is 0.872, sensitivity 79.2 % and specificity 83.3 %), which were derived from plasma exosomes and maintained at high levels in elderly people with MCI, could be employed as promising noninvasive biomarkers.

Relationship between Residential Segregation, Later-Life Cognition, and Incident Dementia across Race/Ethnicity

Systemic racism leads to racial/ethnic residential segregation, which can result in health inequities. We examined if the associations between residential segregation and later-life cognition and dementia differed based on segregation measure and by participant race/ethnicity. Tests of memory (n = 4616), language (n = 4333), visuospatial abilities (n = 4557), and incident dementia (n = 4556) were analyzed in older residents of Northern Manhattan, New York (mean age: 75.7 years). Segregation was measured at the block group-level using three indices: dissimilarity, isolation, and interaction. We fit multilevel linear or Cox proportional hazards models and included a race/ethnicity × segregation term to test for differential associations, adjusting for socioeconomic and health factors. Living in block groups with higher proportions of minoritized people was associated with -0.05 SD lower language scores. Living in block groups with higher potential contact between racial/ethnic groups was associated with 0.06-0.1 SD higher language scores. The findings were less pronounced for other cognitive domains and for incident dementia. Non-Hispanic Black adults were most likely to experience negative effects of neighborhood segregation on cognition (language and memory) and dementia. All indices partly capture downstream effects of structural racism (i.e., unequal distributions of wealth/resources) on cognition. Therefore, desegregation and equitable access to resources have the potential to improve later-life cognitive health.

The Influences of Community-Enriched Environment on the Cognitive Trajectories of Elderly People

To examine the influences of community-enriched environment on the cognitive trajectories of the elderly in China, using panel data of 10,057, 3994, 2387, and 1749 older persons aged 65–104 years of the 2005, 2008, 2011, and 2014 waves from the Chinese Longitudinal Health Longevity Survey (CLHLS) and a growth curve model, the authors analyzed the changing trend of elderly people’s cognitive abilities with age. The influences of community-enriched environments on cognitive abilities were also investigated. Results show that when all the factors are out of consideration except age, for an older person aged 82.5 years, as he/she grows one year older, his/her cognitive abilities will be reduced by 0.139 points, while for one aged 92.5 years, they will be reduced by 0.199 points, which means cognitive abilities decline rapidly as the individuals grow older. The elderly people from communities with enriched environments have higher cognitive levels and slower declining speeds of cognitive abilities than the other elderly people, proving the long-term ability of such environments to facilitate cognitive abilities. An increase in the stimulation of the enriched environment is needed to prevent or slow down the degeneration of cognitive abilities.

Operationalizing Social Environments in Cognitive Aging and Dementia Research: A Scoping Review

BACKGROUND

Social environments are a contributing determinant of health and disparities. This scoping review details how social environments have been operationalized in observational studies of cognitive aging and dementia.

METHODS

A systematic search in PubMed and Web of Science identified studies of social environment exposures and late-life cognition/dementia outcomes. Data were extracted on (1) study design; (2) population; (3) social environment(s); (4) cognitive outcome(s); (5) analytic approach; and (6) theorized causal pathways. Studies were organized using a 3-tiered social ecological model at interpersonal, community, or policy levels.

RESULTS

Of 7802 non-duplicated articles, 123 studies met inclusion criteria. Eighty-four studies were longitudinal (range 1-28 years) and 16 examined time-varying social environments. When sorted into social ecological levels, 91 studies examined the interpersonal level; 37 examined the community/neighborhood level; 3 examined policy level social environments; and 7 studies examined more than one level.

CONCLUSIONS

Most studies of social environments and cognitive aging and dementia examined interpersonal factors measured at a single point in time. Few assessed time-varying social environmental factors or considered multiple social ecological levels. Future studies can help clarify opportunities for intervention by delineating if, when, and how social environments shape late-life cognitive aging and dementia outcomes.

Association of Racial Residential Segregation Throughout Young Adulthood and Cognitive Performance in Middle-aged Participants in the CARDIA Study

Importance

Neighborhood-level residential segregation is implicated as a determinant for poor health outcomes in black individuals, but it is unclear whether this association extends to cognitive aging, especially in midlife.

Objective

To examine the association between cumulative exposure to residential segregation during 25 years of young adulthood among black individuals and cognitive performance in midlife.

Design, Setting, and Participants

The ongoing prospective cohort Coronary Artery Risk Development in Young Adults (CARDIA) Study recruited 5115 black and white participants aged 18 to 30 years from 4 field centers at the University of Alabama, Birmingham; University of Minnesota, Minneapolis; Northwestern University, Chicago, Illinois; and Kaiser Permanente, Oakland, California. Data were acquired from February 1985 to May 2011. Among the surviving CARDIA cohort, 3671 (71.8%) attended examination year 25 of the study in 2010, when cognition was measured, and 3008 (81.9%) of those completed the cognitive assessments. To account for time-varying confounding and differential censoring, marginal structural models using inverse probability weighting were applied. Data were analyzed from April 16 to July 20, 2019.

Main Outcomes and Measures

Racial residential segregation was measured using the Getis-Ord Gi* statistic, and the mean cumulative exposure to segregation was calculated across 6 follow-up visits from baseline to year 25 of the study, then categorized into high, medium, and low segregation. Cognitive function was measured at year 25 of the study, using the Digit Symbol Substitution Test (DSST), Stroop color test (reverse coded), and Rey Auditory Verbal Learning Test. To facilitate comparison of estimates, z scores were calculated for all cognitive tests.

Results

A total of 1568 black participants with available cognition data were included in the analysis. At baseline, participants had a mean (SD) age of 25 (4) years and consisted of 936 women (59.7%). Greater cumulative exposure to segregated neighborhoods was associated with a worse DSST z score (for high segregation, β = -0.37 [95% CI, -0.61 to -0.13]; for medium segregation, β = -0.25 [95% CI, -0.51 to 0.0002]) relative to exposure to low segregation.

Conclusions and Relevance

In this cohort study, exposure to residential segregation throughout young adulthood was associated with worse processing speed among black participants as early as in midlife. This association may potentially explain black-white disparities in dementia risk at older age.

Anti-poverty policy and health: Attributes and diffusion of state earned income tax credits across U.S. states from 1980 to 2020

PURPOSE

The U.S. federal Earned Income Tax Credit (EITC) is often considered the most effective antipoverty program for families in the U.S., leading to a variety of improved outcomes such as educational attainment, work incentives, economic activity, income, and health benefits for mothers, infants and children. State EITC supplements to the federal credit can significantly enhance the magnitude of this intervention. In this paper we advance EITC and health research by: 1) describing the diffusion of state EITC policies over 40 years, 2) presenting patterns in important EITC policy dimensions across space and time, and 3) disseminating a robust data set to advance future research by policy analysts and scientists.

METHODS

We used current public health law research methods to systematically collect, conduct textual legal analysis, and numerically code all EITC legislative changes from 1980 through 2020 in the 50 states and Washington, D.C.

RESULTS

First, the pattern of diffusion across states and time shows initial introductions during the 1990s in the Midwest, then spreading to the Northeast, with more recent expansions in the West and South. Second, differences by state and time of important policy dimensions are evident, including size of credit and refundability. Third, state EITC benefits vary considerably by household structure.

CONCLUSION

Continued research on health outcomes is warranted to capture the full range of potential beneficial effects of EITCs on family and child wellbeing. Lawyers and policy analysts can collaborate with epidemiologists and economists on other high-quality empirical studies to assess the many dimensions of policy and law that potentially affect the social determinants of health.

State-Level Income Inequality and County-Level Social Capital in Relation to Individual-Level Depression in Middle-Aged Adults: A Lagged Multilevel Study

In the US, the incidence of depression and suicide have followed escalating trends over the past several years. These trends call for greater efforts towards identifying their underlying drivers and finding effective prevention strategies and treatments. One social determinant of health that plausibly influences the risk of depression is income inequality, the gap between the rich and poor. However, research on this association is still sparse. We used data from the National Longitudinal Survey of Youth 1979 and the US Census to investigate the multilevel lagged associations of state-level income inequality with the individual-level odds of depression in middle-aged adults, controlling for state- and individual-level factors. We also examined the independent associations of county-level social capital with depression and explored whether it mediated the income inequality relationship. Higher income inequality at the state level predicted higher odds of individual-level depression nearly 2 decades later [OR for middle vs. lowest tertile of income inequality = 1.35 (95% CI: 1.02, 1.76), OR for highest vs. lowest tertile = 1.34 (95% CI: 1.01, 1.78)]. This association was stronger among men than women. Furthermore, there was evidence that county-level social capital independently predicted depression and that it mediated the income inequality association. Overall, our findings suggest that policies attenuating levels of income inequality at the US state level and that leverage social capital may protect against one's likelihood of developing depression.

Neighborhood Environments and Cognitive Decline Among Middle-Aged and Older People in China

OBJECTIVES

Despite the growing interest in the effects of neighborhood environments on cognitive function, most studies on older people are based on cross-sectional survey data from developed countries. This study examines the relationship between neighborhood environments and decline in cognitive function over time among middle-aged and older people in China and whether this relationship varies between rural and urban residents.

METHODS

The three waves of China Health and Retirement Longitudinal Study (CHARLS 2011-2015) were used. The sample included 12,131 respondents living in 298 rural villages and 4,059 respondents living in 150 urban communities. Three-level linear growth curve models were estimated to track trajectories of cognitive change over a 4-year period.

RESULTS

Chinese older people who lived in neighborhoods with more handicap access, more bus lines, employment service, and higher socioeconomic status (SES) had slower cognitive decline. Neighborhood basic infrastructures, number of days that roads were unpassable, outdoor exercise facilities, and average social activity participation were associated with baseline cognitive function in both rural and urban areas, but neighborhood environments had more impact on cognitive decline among rural older adults than urban older adults.

DISCUSSIONS

Findings from this study call for increased infrastructure development and community building programs in rural China.

Social determinants of health in relation to firearm-related homicides in the United States: A nationwide multilevel cross-sectional study

BACKGROUND

Gun violence has shortened the average life expectancy of Americans, and better knowledge about the root causes of gun violence is crucial to its prevention. While some empirical evidence exists regarding the impacts of social and economic factors on violence and firearm homicide rates, to the author's knowledge, there has yet to be a comprehensive and comparative lagged, multilevel investigation of major social determinants of health in relation to firearm homicides and mass shootings.

METHODS AND FINDINGS

This study used negative binomial regression models and geolocated gun homicide incident data from January 1, 2015, to December 31, 2015, to explore and compare the independent associations of key state-, county-, and neighborhood-level social determinants of health-social mobility, social capital, income inequality, racial and economic segregation, and social spending-with neighborhood firearm-related homicides and mass shootings in the United States, accounting for relevant state firearm laws and a variety of state, county, and neighborhood (census tract [CT]) characteristics. Latitude and longitude coordinates on firearm-related deaths were previously collected by the Gun Violence Archive, and then linked by the British newspaper The Guardian to CTs according to 2010 Census geographies. The study population consisted of all 74,134 CTs as defined for the 2010 Census in the 48 states of the contiguous US. The final sample spanned 70,579 CTs, containing an estimated 314,247,908 individuals, or 98% of the total US population in 2015. The analyses were based on 13,060 firearm-related deaths in 2015, with 11,244 non-mass shootings taking place in 8,673 CTs and 141 mass shootings occurring in 138 CTs. For area-level social determinants, lag periods of 3 to 17 years were examined based on existing theory, empirical evidence, and data availability. County-level institutional social capital (levels of trust in institutions), social mobility, income inequality, and public welfare spending exhibited robust relationships with CT-level gun homicide rates and the total numbers of combined non-mass and mass shooting homicide incidents and non-mass shooting homicide incidents alone. A 1-standard deviation (SD) increase in institutional social capital was linked to a 19% reduction in the homicide rate (incidence rate ratio [IRR] = 0.81, 95% CI 0.73-0.91, p < 0.001) and a 17% decrease in the number of firearm homicide incidents (IRR = 0.83, 95% CI 0.73-0.95, p = 0.01). Upward social mobility was related to a 25% reduction in the gun homicide rate (IRR = 0.75, 95% CI 0.66-0.86, p < 0.001) and a 24% decrease in the number of homicide incidents (IRR = 0.76, 95% CI 0.67-0.87, p < 0.001). Meanwhile, 1-SD increases in the neighborhood percentages of residents in poverty and males living alone were associated with 26%-27% and 12% higher homicide rates, respectively. Study limitations include possible residual confounding by factors at the individual/household level, and lack of disaggregation of gun homicide data by gender and race/ethnicity.

CONCLUSIONS

This study finds that the rich-poor gap, level of citizens' trust in institutions, economic opportunity, and public welfare spending are all related to firearm homicide rates in the US. Further establishing the causal nature of these associations and modifying these social determinants may help to address the growing gun violence epidemic and reverse recent life expectancy declines among Americans.

Paid Sick Leave and Risks of All-Cause and Cause-Specific Mortality among Adult Workers in the USA

Background: The USA is one of only a few advanced economies globally that does not guarantee its workers paid sick leave. While there are plausible reasons why paid sick leave may be linked to mortality, little is known empirically about this association. Methods: In a pooled USA nationally-representative longitudinal sample of 57,323 working adults aged 18-85 years from the National Health Interview Surveys 2000-2002, paid sick leave was examined as a predictor of all-cause and cause-specific mortality. Multivariate Cox proportional hazards models were used to estimate the impact of paid sick leave on mortality. Results: Having paid sick leave through one's job was associated with 10% (hazards ratio, HR = 0.90; 95% CI = 0.81-0.996; p = 0.04), 14% (HR = 0.86; 95% CI = 0.74-0.99; p = 0.04), and 22% (HR = 0.78; 95% CI = 0.65-0.94; p = 0.01) significantly lower hazards of all-cause mortality after mean follow-up times of 11.1, 6.5, and 4.5 years, respectively. This study further identified associations of paid sick leave with 24% (HR = 0.76; 95% CI = 0.59-0.98; p = 0.03), and 35% (HR = 0.65; 95% CI = 0.44-0.95; p = 0.03) lower hazards of dying from heart diseases and unintentional injuries, respectively. Conclusions: To the author's knowledge, this study provides the first empirical evidence on the linkages between paid sick leave and mortality and supports protective effects, particularly against heart diseases and unintentional injuries. The most salient association corresponded to a lag period of just less than five years. Social policies that mandate paid sick leave may help to reduce health inequities and alleviate the population burden of mortality among working adults in the USA.